A lot of languages have incorporated the Roman title of Caesar in various ways and I don't know of any that kept both the pronunciation and the spelling. Kaiser, Tsar, Czar, Kayser, Kēsar, Qaisar, Çezar, Ķeizars, Καῖσαρ, قیصر ,קיסר, կայսր, and so on. It entered into English via the Germanic kaisar (or something similar, we don't know a lot about Proto-West Germanic) and shifted over time from cāser to cāsaer to cāsere, and at some point the word started being pronounced with a soft C as English phonology shifted, giving us 'see-sar'. Modern English re-adopted the original Latin spelling but kept the morphed pronunciation.
Funnily enough, the meaning of 'Caesar' didn't even last out the Roman Empire. After Augustus adopted it from Julius to emphasize his connection to him, it shifted from 'heir to Gaius Julius Caesar specifically' to something very roughly equivalent to 'Emperor' to 'designated heir to the Emperor' to a court title unrelated to succession that kept being bumped down in importance as new and more powerful ones were invented.
And if we really want to get pedantic, we need to stop saying 'Gaius Julius Caesar' to mean the old Roman guy in the Asterix comics. Latin didn't have mixed case, it didn't have J or U, and the gens Julia preferred an older spelling for 'Gaius'. So the fellow is 'CAIVS IVLIVS CAESAR'.
(help I've been nerd sniped)